As a sweetener, sucrose (sugar) has heretofore been used broadly on the strength of its sweetness of good quality and good body (a full-bodied mouthfeel), humectant properties and viscosity-imparting characteristics. However, the recent health-mindedness and orientation of the public toward low-calorie intake have cut down on the ingestion of sucrose, which is causative of obesity and dental caries, and particularly in the field of delicacy items such as drinks and desserts, the demand for energy sparing is the order of the day. For this reason, research and development work has been in progress on high-sweetness sweeteners as substitutes for sugar and, among them, sucralose having a sweetness about 600 times as high as that of sucrose is attracting attention as a novel sweetener in view of its being a non-caries-producing, non-metabolizable and non-calorie sweetener.
In contrast to peptide sweeteners such as aspartame, sucralose ranks high in stability. It is reported that particularly in the form of an aqueous solution, sucralose remains exceptionally stable even under high temperature and low pH conditions, retaining a satisfactory sweetness profile (the intensity and quality of sweetness) (M. E. Quinlan, J. Food Sci., 55 (1), 244 (1990)). On the other hand, however, it is known that crystalline sucralose tends to be thermolabile, turning light-brown in color when stored in dry state at elevated temperature and that it is severely decomposed when stored at a temperature of about 40° C. or higher for a protracted time.
For stabilizing sucralose against discoloration under high-temperature and dry conditions and the following methods have so far been attempted.
(1) The method which comprises atomizing sucralose crystals down to a certain particle diameter (Japanese Examined Patent Publication No. 2562147); (2) the method which comprises preparing a mixed solution of sucralose and a water-soluble oligosaccharide in water and spray-drying or freeze-drying the solution to give a sweet concentrate (Japanese Examined Patent Publication No. 2521308); (3) the method which comprises converting sucralose and cyclodextrin to an eutectic complex (Japanese Unexamined Patent Publication H02-258714); (4) the method which comprises converting sucralose and a nitrogen-containing base to an eutectic complex (British Patent GB2169601 “Stabilization of Sucralose”); (5) the method which comprises dissolving sucralose together with a stabilizer (a cellulose or carbohydrate), a buffer (e.g. an organic acid and/or an organic acid salt) and a preservative (e.g. benzoic acid) in water to give a mixed solution and freeze-drying the solution (Japanese Unexamined Patent Publication H04-258269), and (6) the method which comprises stabilizing sucralose with cellulose, calcium carbonate and dicalcium phosphate (Japanese Unexamined Patent Publication H04-228048).
However, the above methods (1) and (2) are disadvantageous in that the attainable stability of sucralose is still insufficient; the methods (3) and (4) are disadvantageous in that because the final product is morphologically limited to a crystalline complex, no versatility can be obtained in the form of usage and limitations on production parameters are also considerable; and the methods (5) and (6) are lacking in universal utility because auxiliary materials not completely soluble in water are included. Thus, a sucralose preparation stabilized against heat and exploitable in a broad range of uses remained to be developed.